JPS59187640A - Polyamide tire cord and production thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simplified method for producing polyamide tire cord (hereinafter referred to as polyamide cord) having high modulus and improved dimensional stability. Polyamide cords have traditionally been useful in automobile bias tires due to their advantages such as toughness and durability. However, in recent years, with the shift in tire structure from bias tires to radial tires, polyamide cords are losing their air quality.Cords for radial tires are particularly required to have high modulus, low dimensions, and performance. Conventional polyamide cords, which are inferior in modulus and dimensional stability, are only partially used in fields where durability is particularly required, and polyester cords and steel cords are mainly used.

However, although polyester cord is useful for small radial tires, it has poor heat resistance, adhesion, and fatigue resistance.
There are concerns about its application to large tires that are used under harsh conditions.

On the other hand, although steel cord has excellent characteristics, it has the drawback of increasing tire weight and reducing fuel consumption. Therefore, it is most preferable to use polyamide cord as a material for relatively large radial tires, especially as a carbon fiber material, because it can maintain its original characteristics while also having the high modulus and dimensional stability of polyester cord, and its development is desirable. It was rare.

However, in addition to achieving the above-mentioned excellent characteristics in terms of quality, it is also possible to manufacture the cord at a lower cost through a process that is simpler than conventional methods, making polyamide cord competitive with other materials. This is necessary to ensure that it is used. This is because the price of organic fibers has increased significantly in recent years, and the rate of increase is especially high for polyamide, which is expected to be disadvantageous in terms of raw material prices in the future. This is because drastic improvements are required in terms of cost as well.

Therefore, the present inventors improved the high modulus and dimensional stability of the polyamide cord while retaining its original properties.
Further, as a result of intensive study on a method of manufacturing the cord at low cost through a simplified process, the present invention was arrived at.

That is, the present invention melt-spun polyamide consisting essentially of polyhexamethylene adipamide at a spinning speed of 5 oon1 n/min or more, and obtained an elongation E of 60% or less and a birefringence Δn of 42
XiO' or more, density ρ is 1168 or more, single filament fineness Df is 15 to 6 deniers, and without drawing, the twisting coefficient K is 2200 to 28oO, and the first and second twists are applied (raw cord and untwisted). This can be achieved by applying an adhesive, applying a 60 to 10% stretch, and subjecting it to tension heat treatment to obtain a tire cord having the following properties.

(B) T/D,'≧6.5g/d (MDE≦8% (C)
to 864%) MDE+HaS≦12% (E)l 19QO, 4≧1000 However, in the above, T/D is strength, MDE is intermediate elongation, △S is 177℃ dry heat shrinkage rate, K is It is a twist coefficient, and its definition and measurement method are as follows.

Birefringence Δn°n was measured using a polarizing microscope model 1QxTp-11 manufactured by Koni Co., Ltd., using white light as a light source, and by the usual Pentz compensator method.

Density ρ: Measured at 25°C using a density gradient tube prepared using carbon tetrachloride as a heavy liquid and toluene as a light liquid.

Strength T/D, elongation E and intermediate elongation MDF: : JI
According to the sacrificial and measurement method of SL1017. 20℃, 65
%Rt (24 hours) in a room adjusted to a temperature and humidity of
:1n, and the tensile rate was 30α/min.

Intermediate elongation MDE: Perform a tensile test on the tire cord in the same manner as T/D of @E to obtain a load-elongation rate curve. In the load-elongation rate curve, the fineness of the raw yarn is D, and the number of twisted yarns is n.
When , the elongation under load is determined and this is defined as MDE.

MDID is a parameter that is used as an indicator of the modulus of a tire cord, and the smaller the MDE, the higher the modulus.

Dry heat shrinkage rate △S° sample was cut into shape, 20℃, 65%
After leaving it for more than 24 hours in a room controlled by RH temperature and humidity,
A sample of length lo, measured by applying a load equivalent to 0.1 g/d of the sample, was left in a 177°C Garp/Instep for 30 minutes without tension, then removed from the oven and placed in the temperature/humidity control room. After being left for 4 hours, the above load was applied again and the measured length 11 was calculated using the following formula.

△S=C(lo ~(1+)/(Jo X 100
(%) Twist coefficient K Number of twists per 10 cIN of processed cord y
2T (however, the number of twists is the average of the number of first and second twists), and the fineness is D, the value is determined by the following formula.

However, the fineness was set to a value without correction based on the amount of adhesive attached.

K=T, /'T Conventionally, proposals have been made for a simplified process in which the fibers are twisted without the stretching process, and the stretching process is included in the tension heat treatment after applying an adhesive. I got it.

For example, there are methods disclosed in Japanese Patent Application Laid-open Nos. 49-133648 and 54-54415. The former is 3000
polyamide or polyester fibers spun at a high speed of 2 m/min or more, the latter at 3000 m/min or more, e.g.
This method uses a nylon 6m fiber obtained by spinning at a high speed of 00 to 4,700 m/min to form a treated cord using the same simplified method as described above.

However, the above method is not practically adopted because the code obtained by the above method does not have characteristics equal to or better than those obtained by a conventional method. In addition, after twisting, it is necessary to take into account the number of twists that will decrease due to stretching during tension heat treatment after applying adhesive, but in this case, the twist coefficient will be lower because the raw cord before stretching has a thicker fineness. The yarn becomes extremely large, causing non-uniform twisting, making it impossible to twist the yarn normally, and causing a significant decrease in strength. In addition, increasing the number of twists may prevent the advantage of the simplified process from being utilized. On the other hand, if the same number of twists as the conventional raw cord is applied, the number of twists will be reduced by the amount of stretching during the tension heat treatment, resulting in particularly poor fatigue resistance.

Therefore, the present inventors solved the above-mentioned contradiction-! As a result of studies conducted to solve the above problems, it was found that the present invention can achieve the above-mentioned problems by 1) producing fibers with significantly improved fatigue resistance and low residual elongation; 2) Even if the treated cord twist coefficient is smaller than the conventional cord, it is possible to obtain a needle with fatigue resistance equal to or higher than that of the conventional cord.
and 5) This became possible for the first time because the length before stretching during the cord tensioning heat treatment was made relatively small. The present invention also proposes a cord design that takes advantage of the high modulus, dimensional stability, etc. that are produced by reducing the twist coefficient.

Next, the present invention will be explained using the drawings.

The drawings show the manufacturing process of the yarn used for the cord of the present invention.

The fiber used in the present invention consists essentially of a polyamide consisting of polyhexamethylene adipamide, and contains a copolymer or blend polymer containing 95 mol % or more of hexamethylene adipamide units. Examples of polymer components that can be copolymerized include ε-capramide, hexamethylene sebacamide, hexamethylene terephthalamide, hexamethylene isophthalamide, etc., and examples of polymers that can be blended include ε-capramide, hexamethylene sebacamide, hexamethylene terephthalamide, and hexamethylene isophthalamide. There is a polymer that In order to obtain the high strength tire cord of the present invention, the temperature must be 25°C.
A high polymerization degree polymer having a sulfuric acid relative viscosity of 60 or more measured at 1% by weight of the polymer is used. It also usually contains heat-resistant agents used in industrial polyamide fibers, such as inorganic or organic copper salts, alkali metal halides, alkaline earth metal halides, inorganic or organic phosphorus compounds, amine or phenolic antioxidants, etc. and includes one or more of these.

The above polymer is melt-spun, using an extruder-type spinning machine, for example, to a temperature higher than the melting point of the polymer, e.g.
Spun at 20°C.

The thread (y) spun through the spinneret (1) is cooled and solidified by being blown with cold air by the cooling chimney (3), and then lubricated with a take-up roll (5.6J
After determining the speed, it is rolled up.

In order to improve the spinning stability, a slow cooling zone (a) is provided directly below the spinneret with a thickness of 5 to 50 cM, preferably 10 to 40 cM. Usually, a cylindrical heating cylinder (2) with a length of 5 to 30 pieces is attached. The yarn that has passed through the slow cooling zone is rapidly cooled with cold air at 10 to 40°C by the cooling chimney installed below the heating cylinder.

The polyhexamethylene adipamide polymer of the present invention is melt-spun and remains in the crystallization temperature range for a long period of time until it is solidified, producing spherulites, deteriorating the spinning drawability and decreasing the strength and elongation. . Therefore, when paying attention to the above-mentioned quenching method, it is necessary that the single yarn fineness of the drawn yarn does not exceed a certain thickness. That is, 15 to 60 denier (dJ.6゜6
In the above case, the formation of spherulites is significant and the fiber is unsuitable as a yarn for the cord of the present invention. If it is less than 1.5 d, yarn wobbling, single fiber collision, etc. will occur during spinning, and normal spinning will not be possible.In addition, within the spinning range of the present invention, the fineness of single fibers should not exceed a certain level (by straining and preventing spherulite formation). Therefore, the amount of polymer discharged from the nozzle per hole (hereinafter referred to as single hole discharge amount) is 10~
The rate is 30 g/min, preferably 15 to 2.5 g/d.

The spinning speed is such that △n is 42 x 10-' or more, preferably 45Xi O' or more, and ρ is t i 58 in terms of the characteristics of the drawn yarn.
g/CC or more, or 1140 g/Cr or more,
E is determined to be 60% or less, preferably 50% or less.

The characteristics of the drawn yarn depend on the conditions of the slow cooling zone after spinning (length,
(temperature), degree of quenching, and single yarn; 1 degree spinning parameter (e) varies depending on this, but usually 501 J Om/min or more.
2, the above characteristics can be obtained. A more preferable spinning speed is 65
00 m 7 minutes or more.

If a yarn that does not satisfy the above characteristics is used, in order to satisfy the characteristics of the polyamide cord of the present invention, 3 steps after twisting will be required.
4. It is difficult to pass through the cord without harm, or satisfactory polyamide cord properties cannot be obtained. The upper limit of spinning speed is increasing with the development of spinning take-off technology and equipment, but is currently possible up to 8500 m7 minutes.

The above-mentioned drawn yarn (original yarn) is once wound up by the winding machine (7), and after combining several yarns as necessary so that the final treatment cord fineness matches the target fineness, or after combining them, they are combined and twisted. Use raw code. The first twist and the first twist are in opposite directions, and the twist coefficient is
is in the range of 220D to 2800. The twist coefficient of the raw cord is 1, which is a value determined by the following equation.

K+ = T17 lower T (here, T1 is the number of twists per 10 m, and Dl is the fineness of the raw cord) If the twist coefficient of 1 exceeds 2800, double twist may occur, or the strength of the cord of the present invention when treated cord is I can't reach this.

On the other hand, when is less than 220θ, the fatigue resistance of the treated cord is poor and the object of the invention cannot be achieved.

-12- Next, the 2nd grade student code can be changed as it is or once it is sudare woven.
After straining, it is passed through a dip solution to apply adhesive, and then subjected to tension heat treatment. The adhesive used is ordinary resorcinol, formalin, and latex liquid. The amount of adhesive applied is about 2 to 5%, which is the same as that of conventional cords. The cord then passes through a drying zone and is then subjected to tension heat treatments, which are usually carried out successively.

Conventional cord tension heat treatment is approximately 1.0% in the hot zone.
After applying the stress, the material is subjected to a stress or relaxation heat treatment of a few percent or less in a normal zone. The tension heat treatment of the cord of the present invention has a stretch rate of 50 to 100%, preferably 50 to 7.
0%, which is i% lower than the conventional code processing. Therefore, when using conventional equipment, consider the distribution of stretching L6
It is preferable to do so. For example, it is preferable to perform stretching of 30% or less even in the dry zone.

The pretreatment temperature in each zone basically does not need to be changed from that when processing conventional cords, but the cords of the present invention do not undergo the same thermal history during stretching as conventional cords.
Since only a portion of the product has been processed, it is preferable to slightly increase the product temperature and/or heat treatment time. For example 225-245
℃, and the residence time is preferably 80 to 240 seconds\
.

The cord of the present invention has high modulus and improved dimensional stability, and high modulus means that the shrinkage rate is low, so the tension rate is increased and dimensional stability is maintained even as a high modulus cord.

In other words, even if the tire is subjected to heat shrinkage treatment during the tire molding process, the shrinkage rate is small, so the original cord modulus is relatively maintained.

Therefore, in the present invention, the processing code 1zi) M D E is changed to 8
% or less. The preferred MDE range is 55-75%. In the conventional code, "2nd MD"
If the treatment is carried out to obtain E, the yield rate will be affected and the fatigue resistance will also be significantly lowered, so there is no point.

The code of the present invention processed so that the MDK becomes as described above has the following characteristics.

(a) T/D≧6.5g/d (b) MDE≦8% (c) HaS≦4% (d) MDE +△S≦12%1M)1
9002≧1000 That is, the cord of the present invention is characterized in that MDE, ΔS, and K are each smaller than those of the conventional tire cord.

It also possesses the characteristics of conventional polyamide cords, such as high strength, high adhesiveness, and high fatigue resistance.

By taking advantage of the above-mentioned useful properties, the polyamide tire cord of the present invention can be used for purposes other than tire cords, such as rubber reinforcing materials for V-belts, timing belts, conveyor belts, etc., and reinforcing materials for resin-coated base fabrics. .

The present invention will be explained below with reference to Examples.

Example 1 A polyhexamethylene adipamide polymer having a sulfuric acid 4-viscosity ratio of 52 and containing 0.05% by weight of copper acetate and 10% by weight of potassium iodide as heat-resistant agents was melt-spun using an extruder-type spinning machine.

Using the apparatus a shown in FIG. 1, the polymer temperature was 300° C., and the die had a hole diameter of 05 φ and 96 holes.

A heating tube with a length of 20 mm was attached directly below the cap, and the ambient temperature (temperature measured at a position 1 tube from the outermost thread) was set at 500°C. Since the degree of the cap surface was 5~5, the annealing zone from the cap surface to the bottom end of the heating cylinder was 25 m. An annular chimney with a length of 40α was attached to the bottom of the heating cylinder via a 1 m heat insulating plate, and 25° C. cold air was uniformly blown from the outer circumference of the yarn at a wind speed of 40 m/min to rapidly cool the yarn. After the yarn is solidified, it is lubricated with a guide lubricant, and then transferred to the TGR12, which rotates at the same speed.
It was taken over by G RiC at a spinning speed of 75 [10 m/min] and was once wound up by a winding machine.

In non-tests, the amount of polymer discharged was changed and yarns with different finenesses were spun. After the obtained drawn yarn was double-twisted, the first twist and the second twist were performed by changing the number of twists to obtain a raw cord. The number of yarns to be folded was determined by back calculation so that the fineness of the treated cord would be approximately 27,006, which is the same as that of the conventional cord. Next, the raw code is RF-processed using a Combutreater (manufactured by Rinolar Co., Ltd. (USA)).
After being immersed in the L solution, it was dried in a dry oven at 160°C for 80 seconds, then heat-treated in a hot zone at 240°C for 80 seconds and then in a normal zone at 240°C for 80 seconds. The cord was stretched in each treatment zone and tension heat treated to a predetermined MDE.

For comparison, the spinning speed was 5 s obtained using the same method as above.
o o m/fl yarn and commercially available polyhexamethylene adipamide fiber for tire cord (+260 tenier, 204
Two filaments (filaments) were twisted together, applied with adhesive, and subjected to tension heat treatment.

When the twist coefficient and tension heat treatment were carried out under the conditions of the present invention using drawn yarn having specific physical properties not disclosed in the invention, a polyamide tire cord having excellent, well-balanced properties was obtained.

[Brief explanation of drawings]

The drawing shows the manufacturing process of the yarn used for the cord of the present invention. 1...Base 2...Heating cylinder 20...Slow cooling zone 3... Cooling chimney 4...Lubrication device 5... Pick up roll ６　・・・Collection body roll 7... Winding machine Y... Thread

Claims (1)

[Claims] Polyamide consisting essentially of polyhexamethylene adipamide is melt-spun at a spinning speed of 5 o o o m/min or more, and has an elongation E of 60% or less and a birefringence △n of 42Xi. O
``The density ρ is 1138 (g/work) or more'' 2. The multifilament with a single yarn fineness Df of 15 to 6 deniers is subjected to ply twisting and first twisting with a twist coefficient K of 2200 to 2800 without drawing. A method for manufacturing a polyamide tire cord, which comprises forming a raw cord, applying an adhesive, stretching the cord by 30 to 100% and subjecting it to tension heat treatment to obtain a treated cord having the following properties. (B) T/D ≧ 6.5g/d (mouth I
MDE ≦ 8% (c) △S ≦
4 % + MDE + S≦ 12 1st-k) 19
00 ≧ K, E: 1000 (T/l in (a) to 0s above) is strength, MDK is intermediate elongation, △S is 1
It is the dry heat shrinkage rate at 77°C, and the definition and measurement method are as described in the text. )